Match the following.

List-I	List-II
a. Research design formulated for discovering new facts	1. Descriptive research design
b. Some specific variables are studied	2. Diagnostic research design
c. It refers to the exact nature and scope of the problem under investigation and then suggest remedies against it	3. Experimental research design
d. Events are observed about which a prediction is to be made in respect of both experimental and controlled group	4. Exploratory research design